[GRASS-dev] PostGIS manager for GRASS GIS

[Mohit Kumar]

Hi all,
Shall I go with this PostGIS manager proposal and apply on melange 
website?
Any further suggestions are welcome
Only one day is left to appply.

Thanks and regards,
Mohit

On Wed, 04 Apr 2012 01:56:17 +0530, Mohit Kumar wrote:
> Hello Martin,
> Sorry couldn't reply earlier as I was stuck with some college work.
>
> On Mon, 2 Apr 2012 21:00:51 +0200, Martin Landa wrote:
>> Hi,
>>
>> 2012/4/2 Mohit Kumar <mohit.kumarug08 at students.iiit.ac.in>:
>>>>> I am interested in making a PostGIS manager in GRASS as a GSoc 
>>>>> 2012 task.
>>>>> PyGreSQL is a python module that allows easy use of database 
>>>>> operation
>>>>> API
>>>>> from a pyhton script. So it will be like a wrapper over
>>>>> the database. This can be done using wxPython and will be OS 
>>>>> independent.
>>>>> Sorry to bug you all, but I am very much interested in developing 
>>>>> for
>>>>> GRASS.
>>
>> [...]
>>
>>>> there is new development ongoing for this in GRASS 7, perhaps a 
>>>> good
>>>> moment to integrate a manager. Maybe Martin has some insights for
>>>> us over the next days.
>>
>>> Its good to know that development is ongoing for this in GRASS, I 
>>> sincerely
>>> want to work on this as my GSoc task.
>>
>> the current PostGIS-related development in G7 is not much related to
>> this idea. The vector engine in G7 is currently able to read PostGIS
>> geometry data natively without any abstract level (like 
>> OGR-PostgreSQL
>> driver). Also write support has been recently implemented. The 
>> current
>> implementation is focused on simple feature access, GRASS builds a
>> pseudo-like topology as for OGR links (see v.external). At this 
>> moment
>> I am working on PostGIS topology support in GRASS.
>>
>>> I have made a brief idea for the manager. The following are the 
>>> various
>>> modules of the manager
>>> 1. Setup connection : This module will set up the connection with 
>>> the remote
>>> database. It will take the input parameters from user and pass them 
>>> to a
>>> connection string. After the connection has been established, the 
>>> user will
>>> be shown the various tables(maps) that are stored and other 
>>> information
>>> about the database and the connection
>>
>> This is already available in wxGUI [1]. Of course there is always a
>> space for any kind of improvements. But basically it's already 
>> there,
>> to add widgets for entering username and password is quite easy 
>> task.
>>
>>> 2. View and edit data : This will display the data of the table in 
>>> a window
>>> frame. One can view the map and modify the table values or the 
>>> attributes.
>>
>> Also possible in current wxGUI [2]. You just create a link using
>> `v.external` and display the map in the map canvas as normal GRASS
>> vector map. Also direct OGR access [3] is possible (no links,
>> pseudo-topology built on the fly)
>>
>>> 3. Import to GRASS Data : This gives the user an option to save the 
>>> data in
>>> Grass format for further processing/analysis of the data. This also 
>>> gives
>>> user an option to discard the data which is of no use.
>>
>> Possible with `v.in.ogr`. Simple wrapper based `v.in.ogr` for
>> importing PostGIS is already there [4].
>>
>>> 4. Execute PostGis functions (geometry processing)on database and 
>>> save
>>> output in grass data format.
>>
>> This could be improvement.
>>
>>> 5. SQL interface : This provides the advanced user to modify the 
>>> database by
>>> use of direct SQL commands on the database.
>>
>>> 6. Export GRASS data to PostGIS data : Convert the Grass Data to 
>>> SQL
>>> database. First convert the Grass data to Esri Shapefile(.shp) 
>>> using OGR and
>>> then converting that data to SQL database (shape2sql).
>>
>> Why?? You can export data directly using `v.out.ogr` [5]. No need 
>> for
>> Shapefiles, that's bad idea.
>>
>>> 7. Projection support : I was also thinking of adding projection 
>>> support to
>>> the manager.
>>
>> In which sense, do you mean on-the fly re-projection (ST_transform)?
>>
>> Martin
>>
>> [1]
>> 
>> http://grass.osgeo.org/wiki/Working_with_external_data_in_GRASS_7#Using_wxGUI
>> [2]
>> 
>> http://grass.osgeo.org/wiki/Working_with_external_data_in_GRASS_7#Digitize_OGR_layer_using_wxGUI
>> [3]
>> 
>> http://grass.osgeo.org/wiki/Working_with_external_data_in_GRASS_7#Direct_access_to_external_data
>> [4] http://grass.osgeo.org/wiki/PostGIS#Import_into_GRASS
>> [5] http://grass.osgeo.org/wiki/PostGIS#Export_to_PostGIS
>
> Thanks for your feedback.
> I know that various modules are possible in GRASS wxGUI. I want to
> integrate them all and provide a direct interface for them. Regarding
> data Export I was thinking about 'v.out.ogr' only.
> And I was talking about on-the fly re-projection. The projection
> tables can be stored in which ever way the user wants.
> What more would you like to add to the current idea to make it worth
> for a GSOC proposal?
> Looking forward to your support.
>
> Regards,
> Mohit Kumar (mohitkharb on irc)
> Lab For Spatial Informatics
> International Institute of Information and Technology
> Hyderabad, India
> +91-970-3840-175
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Mohit Kumar (mohitkharb on irc)
Lab For Spatial Informatics
International Institute of Information and Technology
Hyderabad, India
+91-970-3840-175